This application is based on French Patent Application No. 00 10 527 filed Aug. 10, 2000, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. xc2xa7119.
1. Field of the invention
The invention relates to a device for transmitting electromagnetic signals across a structure including functional modules organized so that two-for-one redundancy is obtained.
The device is intended to be integrated into the equipment units of a system in which signals are transmitted by means of electromagnetic waveguides, for example in communication equipment units on board satellites. In the present context the expression xe2x80x9celectromagnetic waveguidesxe2x80x9d means waveguides proper and functionally equivalent propagative hardware connections, for example microstrip lines.
2. Description of the prior art
For security reasons, equipment units for on board satellites include functional modules that are duplicated so that failure of one module can be remedied by switching on an identical or similar module that duplicates it.
This kind of redundancy is known as two-for-one redundancy and is conventionally applied to various modules included in an equipment unit, for example amplifier modules which operate on signals transmitted via waveguides.
FIG. 1 is a diagram showing one example of a prior art device made up of identical functional modules enabling two-for-one redundancy to be obtained. The device is designed for use in an equipment unit in which signals are transmitted via electromagnetic waveguides. The device shown includes two identical modules 1 and 1xe2x80x2, each of which consists of an amplifier, for example, and the modules are mounted in the device so that they can receive a signal, for example a microwave signal, at an input IN of the device that is connected to the two modules in the equipment unit, not shown here, that incorporates them.
Each of the two modules 1 and 1xe2x80x2 in the equipment unit is adapted to supply an identical signal to an output OUT of the device derived from the signal that it receives at the input IN.
A switch 2 is inserted between the input IN and inputs 11 and 11xe2x80x2 of each module. The switch is conventionally a single-pole double-throw (SPDT) switch for selectively connecting the input IN to one or other of the inputs 11 and 11xe2x80x2. The modules 1 and 1xe2x80x2 each have a signal output O1 or O1xe2x80x2 which is connected to the output OUT of the device via a coupler, for example a single-pole switch 3, configured in the opposite way to the switch 2, for selectively connecting the output OUT to one or the other of the two outputs O1, O1xe2x80x2.
FIG. 2 shows a variant of the prior art device shown in FIG. 1. This variant of the device differs from the previous one in that it includes a Wilkinson circuit substituting a combiner 4 for the single-pole switch previously provided between the outputs of the duplicated modules 1, 1xe2x80x2 and the output OUT of the device. The combiner 4 includes a resistor 5 inserted between the respective outputs O1 and O1xe2x80x2 of the modules 1 and 1xe2x80x2. This is known in the art.
Both the devices shown transmit electromagnetic signals by means of electromagnetic waveguides across a structure including functional modules organized so that two-for-one redundancy is obtained. These devices have the drawback of being bulky, especially if the wavelengths of signals in the target range of wavelengths are relatively high. Moreover, the presence, in addition to the modules, of two switches or of one switch and a combiner complicates incorporating the modules into the same structure. It also complicates testing devices made in this way. This is a major disadvantage, in particular in the case of devices intended for use in equipment units on board satellites, where space is restricted and simple solutions are required for maximum reliability. The invention therefore proposes a device for transmitting electromagnetic signals via electromagnetic waveguides across a structure including functional modules organized so that two-for-one redundancy is obtained.
The invention provides a device for transmitting electromagnetic signals across a structure including functional modules organized so that two-for-one redundancy is obtained, in the case of signals that are transmitted by electromagnetic waveguides, which device includes a waveguide, an input end of which receives signals intended to be fed to one or the other of two functional modules organized so that two-for-one redundancy is obtained, and the other end of which is short circuited, and which includes two electric field sampling units, each of which is adapted to feed one of the modules and which are disposed at respective distances from the short circuited end of the waveguide that are equal to one quarter of the wavelength of the signals transmitted by the waveguide or an odd number multiple thereof, wherein each module has an output connected to a single-pole switch or combiner transmitting signals from either or both of the two modules downstream of the device.
In one embodiment of the invention the two sampling units are plungers having conductive rods that penetrate to the interior of the waveguide via holes formed in the wall of the waveguide, are coplanar and at respective distances from the short circuited end of the waveguide that correspond to one quarter of the wavelength of the electromagnetic signals that the waveguide transmits and to an odd number multiple of one quarter of the wavelength.
In a preferred embodiment the distance between the sampling units along the waveguide is equal to half the wavelength of the electromagnetic signals transmitted by the waveguide.
A different embodiment of the device includes a selective filter in the waveguide that divides it into two cavities in the part of the waveguide that is closed off by a short circuit component, and the filter can be a finned line filter.
In one embodiment of the device according to the invention the modules are formed simultaneously on the same substrate on which they are connected to the plunger rods of the sampling units by microstrip connections.